Description of substance: Oily, colorless to light-yellow liquid with a peppermint- or honey-like odor.

LEL: . 1.4% (10% LEL, 1,400 ppm)

Original (SCP) IDLH: 5,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that 5,000 ppm might be dangerous to life in 30 to 60 minutes [Smyth et al. 1942].

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA:

Lethal concentration data:

Species

Reference

LC50

LCLo

Time

Adjusted 0.5-hrLC (CF)

Derived value

RatRat

Mouse

G. pig

Carpenter et al. 1949Izmerov et al. 1982

Izmerov et al. 1982

Specht et al. 1940

1,000 mg/m39,000 mg/m3

10,000 mg/m3

2,000 mg/m3

———-

—–

—–

4 hr4 hr

2 hr

7 hr

2,000 ppm (2.0)18,000 ppm (2.0)

16,000 ppm (1.6)

4,800 ppm (2.4)

200 ppm1,800 ppm

1,600 ppm

480 ppm

Lethal dose data:

Species

Reference

Route

LD50(mg/kg)

LDLo(mg/kg)

Adjusted LD

Derived value

RatRabbit

Mouse

Hann &Jansen 1974Hann & Jansen 1974

Izmerov et al. 1982

oraloral

oral

1,1201,000

710

———-

—–

1,922 ppm1,716 ppm

1,218 ppm

192 ppm172 ppm

122 ppm

Human data: The probable response to 100 ppm was predicted to be eye and mucous membrane irritation, difficulty breathing, headache, and vertigo [Shell 1957]. It has been stated that 5,000 ppm might be dangerous to life in 30 to 60 minutes [Smyth et al. 1942].

Revised IDLH: 1,400 ppm [LEL]Basis for revised IDLH: Based on health considerations and acute inhalation toxicity data in humans [Smyth et al. 1942], a value of about 4,000 ppm would have been appropriate for mesityl oxide. However, the revised IDLH for mesityl oxide is 1,400 ppm based strictly on safety considerations (i.e., being 10% of the lower explosive limit of 1.4%).